Petrographic Studies of Potash Feldspar from the Yamato Sanmyaku, East Antarctica

The Yamato Sanmyaku is a mountain range located about 200km south of Prins Harald Kyst, East Antarctica. The mountains are composed of charnockitic group and granitic group rocks which were described geologically and petrographically by K. KIZAKI (1965). The present paper deals with the potash feldspars from the charnockitic group and pegmatites. The occurrence of the potash feldspars and their optical characteristics are described first, revealing the mechanism of albitization of potash feldspars which have a wide range in the optical axial angle. Next, the two-feldspar geothermometry method is applied to the potash feldspars from the Yamato Sanmyaku and the results are compared with that of the Norwegian potash feldspars and also with the data of Japanese plutonic rocks. The formation temperatures estimated from the distribution coefficient k, triclinicity and 2Vx value are discussed on the basis of the subsolidus phase relation, the relation between the formation temperature and crystal symmetry, and the relation between the optical axial angle and triclinicity. These relations well support the conclusion held from the geological and petrographical points of view that the charnockitic rocks were originally formed under a granulite facies condition, but their characters were influenced more or less by the subsequent granitization under an amphibolite facies condition

Identification of an inter-transcription factor regulatory network in human hepatoma cells by Matrix RNAi

Transcriptional regulation by transcriptional regulatory factors (TRFs) of their target TRF genes is central to the control of gene expression. To study a static multi-tiered inter-TRF regulatory network in the human hepatoma cells, we have applied a Matrix RNAi approach in which siRNA knockdown and quantitative RT-PCR are used in combination on the same set of TRFs to determine their interdependencies. This approach focusing on several liver-enriched TRF families, each of which consists of structurally homologous members, revealed many significant regulatory relationships. These include the cross-talks between hepatocyte nuclear factors (HNFs) and the other TRF groups such as CCAAT/enhancer-binding proteins (CEBPs), retinoic acid receptors (RARs), retinoid receptors (RXRs) and RAR-related orphan receptors (RORs), which play key regulatory functions in human hepatocytes and liver. In addition, various multi-component regulatory motifs, which make up the complex inter-TRF regulatory network, were identified. A large part of the regulatory edges identified by the Matrix RNAi approach could be confirmed by chromatin immunoprecipitation. The resultant significant edges enabled us to depict the inter-TRF TRN forming an apparent regulatory hierarchy of (FOXA1, RXRA) → TCF1 → (HNF4A, ONECUT1) → (RORC, CEBPA) as the main streamline